Rapid eye movement sleep deprivation disrupts context-modulated effects on morphine locomotor sensitization in mice

Previous studies have shown that behavioral sensitization is modulated by drug-associated context, in which memory processes may be critically involved. Sleep has been suggested to play an important role in memory processes. However, the relationship between sleep and context-modulated effects on behavioral sensitization remains to be elucidated. In the present study, we designed three experiments to explore the effects of rapid eye movement sleep deprivation (RSD) on context-modulated effects on morphine locomotor sensitization in mice. Mice were subjected to 6 h RSD starting either immediately after morphine pairing training or 6 h later. The control mice were returned to their home cages immediately after pairing training and left undisturbed. In experiment 1, RSD from 0 to 6 h but not from 7 to 12 h disrupted paired context-modulated enhancement of locomotor activity. In experiment 2, RSD from 0 to 6 h but not from 7 to 12 h disrupted unpaired context-modulated suppression of locomotor activity. In experiment 3, RSD from either 0 to 6 h or 7 to 12 h had no effect on conditioned locomotor activity. Our findings suggest that sleep plays a critical role in memory processes underlying context-modulated effects on morphine locomotor sensitization.

► We tested the effects of post-pairing training RSD on morphine behavioral sensitization.
► RSD from 0 to 6 h disrupted paired context-modulated enhancement of locomotor activity.
► RSD from 0 to 6 h disrupted unpaired context-modulated suppression of locomotor activity.
► RSD from either 0 to 6 h or 7 to 12 h had no effect on conditioned locomotor activity.